Show HN: I 3D scanned the interior of the Great Pyramid at Giza

This is really really cool! I enjoyed the explanations as well as the fantastic images

The page crashes for me on iOS.

That's cool!

Thanks for sharing it!

I've used the BLK 360 before so some comment here. Essentially you scan at various points within the volume of interest, e.g. you walk around, place the scanner, scan, repeat. Each scan takes a few minutes at high angular resolution. Leica provides software called Register (or Cyclone) to match the scans together. Because you generally don't have GPS (the BLK doesn't have a GPS onboar and GPS is anyway much more inaccurate than the scan resolution - metres versus millimetres), the software has to do some kind of feature matching to stitch the scans. You get "links" between adjacent scanning points, and then you do a big optimisation pass to combine the scans.

This scan matching is by far the most difficult and time consuming bit. Probably OP had to manually align the scans as a first pass and then the software takes over using some algorithm like ICP (iterative closest point).

This is still only "internal" (i.e. scans are correct relative to each other, but you don't know where the full scan is) and you'd have to combine with an external reference point to geo-locate in the world. Doesn't really matter for this because you're just viewing the pyramid on its own, and you're not overlaying on a map. If you were, then usually what you have to do is take several ground control point (GCP) that are known with high accuracy and then reference that in the scan. You could geo-reference these using an RTK GPS or something, but it's quite difficult to get world coordinates at the millimetre scale and it rarely matters if you're that precise as long as the scan itself is consistent.

This video from Leica shows the full workflow for a typical use case (scanning a house with indoor and outdoor points). Note the point where they link inside and outside, around 16 mins in https://www.youtube.com/watch?v=AV0LPKowOXU

Same! iPhone 12 on latest iOS.